The default user name is determined by the AMI that was specified when we launch the instances. These are the commonly used AMIs along with the default user names.
| Image Name | User Name |
| Amazon Linux2/ Amazon Linux AMI | ec2-user |
| Ubuntu AMI | ubuntu |
| Centos AMI | centos |
| Debian AMI | admin root |
| Fedora AMI | ec2-user fedora |
| SUSE AMI | ec2-user root |
| Others | ec2-user root |
| None of the Above | check with the AMI provider |